(1) Field of the Invention
This invention relates to inhibiting corrosion of metals in oil field applications where hydrocarbons and water are being taken from producing wells. Water may, of course, lead to corrosion of metal piping, etc., which is used in downwell applications. It is, therefore, necessary to add a suitable agent to the oil/water medium to effectively reduce or eliminate problems which are associated with corrosion of metallic parts. Failure to do so results in extensive corrosion of metal in the field leading to expensive repairs and lost productivity.
(2) Description of the Prior Art
Currently employed formulations which are effective in reducing corrosion in oil well piping consist of materials which are produced by the thermal condensation of functionalized C-18 fatty acids (containing one or two double bonds, e.g. oleic and linoleic, respectively). Examples of the methods by which the thermal polymerization of fatty acids occurs include heating an appropriate fatty acid, e.g., tall oil fatty acid or soya fatty acid, in the presence of a clay or other suitable catalyst to give varying amount of C-36 (dimerized) and C-54 (trimerized) fatty acid. This produces a material which when used in the oil field applications provides reasonable protection to the metals present. High molecular weight has been of presumed importance in attaining film persistency due to the nature of the molecule, i.e., multiple bonding sites and a large fatty backbone. For instance, dimer/trimer mixes perform considerably better than their monomeric counterparts. Normally, when the dimer/trimer mixtures are employed they are co-formulated with materials such as fatty acid imidazolines and certain oils. This maximizes performance in the materials to a great degree. Although there is a considerable history of use of dimer/trimer formulations, there is still a considerable call for materials which show a better cost performance profile than those materials currently in use.